US President Barack Obama arrives today in Malaysia hoping to energise aloof ties with a Muslim-majority nation whose government is under the microscope for wide allegations of abuse of power and the loss of Malaysia Airlines flight MH370.

After stops in Japan and South Korea, Obama becomes the first serving US president to visit Malaysia since Lyndon Johnson in 1966 as he tours Asia to fortify alliances amid concern over China's rise and push his troubled plans for a Pacific-wide trade pact.

Battling image problems in the Islamic world, Washington is keen to emphasise its relations with economically successful, moderate-Muslim Malaysia.

But while seeking warmer US ties, Malaysia also is a close trading partner of China and has resisted key aspects of Obama's Trans-Pacific Partnership (TPP) agreement.

The president, who arrives late today afternoon -- is expected to try to ease Prime Minister Najib Razak's concerns on the trade deal.

But crises elsewhere in the world, especially the confrontation with Russia over Ukraine, have distracted Obama from the main objectives of a trip meant to emphasise US engagement with Asia.

Obama will tread a fine line between courting Najib and acknowledging the huge numbers in multi-cultural Malaysia who are fed up with the corruption-plagued coalition in power for 57 years.

Opposition leader Anwar Ibrahim called the government a "corrupt and authoritarian regime" in a statement today that urged Obama to stand up for "freedom and democracy."

"It would be an opportune moment to live up to the ideals Obama espoused in his campaign and the early days of his administration," Anwar said.

US-Malaysian relations remain coloured by bickering during the 1981-2003 tenure of authoritarian leader Mahathir Mohamad, a harsh critic of US policies, though trade ties have remained solid.

Najib, who portrays himself abroad as a reformer and religious moderate, has sought to improve US relations.

But he faces growing criticism for harassing opponents and stifling free expression, particularly after elections last year in which the government lost the popular vote to Anwar's opposition.

Najib clung to power via what critics say is a skewed electoral system favouring his coalition.